The present invention relates to a sounder adapted for use in speakers, alarms, or horns and, more specifically, to such a sounder, which eliminates the drawbacks of complicated structure, low performance and bulky dimension of conventional speakers that comprise speaker shell, end block, magnet, coil, cone, vibration dust diaphragm, etc.
In the modern society, different voice frequency devices have been disclosed, and are intensively used to transmit voice message. These voice frequency devices include simple sound heads for producing sound and speakers for amplifying sound.
The performance of an audio system depends on the quality of its main unit, amplifier, and speakers. More particularly, the speakers of an audio system determine the quality of output sound. A speaker converts electric voice signal into sound audible to the ears. FIG. 1 illustrates the structure of a conventional speaker. As illustrated, the speaker comprises a casing 10, a paper cone 12, and vibration dust diaphragm 13. The casing 10 comprises an outwardly expanded front bracket 14 and a rear end block 11. The rear end block 11 defines a receiving chamber 15, which receives a magnet 16, and a coil 17 around the magnet 16. The paper cone 12 is adhered to the bracket 14. A gasket ring 19 is adhered to the bracket 14 and a part of the paper cone 12. The paper cone 12 has a hole 18 aimed at the magnet 16. The vibration dust diaphragm 13 is adhered to the paper cone 12 and covered over the hole 18. The coil 17 has lead-out wires 171 extended through the paper cone 12 and connected to power source connector (not shown). After power signal has been transmitted to the magnet 16, different current signals are provided to the magnet 16, causing the magnet 16 to move lefts and rights at different distances, thereby causing the vibration dust diaphragm 13 and the paper cone 12 to vibrate and the produce audible sound. There is known another structure of speaker in which metal voice coil is directly installed in the receiving chamber 15 and adapted to produce sound when electrically connected. These conventional speakers are still not satisfactory in function. The drawbacks of these conventional speakers are outlined hereinafter:
1. Complicated structure: As indicated above, a conventional speaker is comprised of a casing, a magnet, a coil, an end block, a paper cone, a vibration dust diaphragm, and etc. According to conventional designs, the coil acts on the magnet subject to the volume of electric current, causing the magnet to displace, so as to further vibrate the vibration dust diaphragm and the paper cone. A speaker constructed subject to this structure is complicated.
2. Bulky and heavy: The installation of the end block and the magnet greatly increases the weight of the speaker. The end block protrudes over the rear side of the speaker, and adapted to support stable displacement of the magnet. Because the end block supports stable displacement of the magnet, it has a certain weight.
3. Low heat dissipation effect and high sound wave distortion: Because the vibration dust diaphragm seals the receiving chamber to achieve a sound box effect, it prohibits quick dissipation of heat from the receiving chamber, and accumulation of heat may cause distortion of sound waves.
The sound head of a broadcasting or alarm speaker produces sound by means of potential difference. A broadcasting or alarm speaker is portable and, effective to produce high level of sound. FIG. 2 shows a sound head according to the prior art design. As illustrated, an annular rib 23 is provided at the front side of the shell 20 to support a cone 24, and a cover 21 with sound holes 22 is covered on the front side of the shell 20. A sound disk 26 is adhered to the rear end of the cone 24 by bonding glue 25. The sound disk 26 has a circuit (piezoelectric transducer) on it, and lead-out wires 27 for connection to power source. When electrically connected, potential differences cause vibrations to produce sound. Because the sound disk 26 has its center area adhered to the cone 24, the vibration of the sound disk 26 is constrained. Further, because the amplitude of the sound disk 26 is limited and far away from the cone 24, the transmission of sound effect is less efficient.
The present invention has been accomplished to provide a sounder, which eliminates the drawbacks of the aforesaid conventional designs. According to one aspect of the present invention, the sounder is comprised of a cone and a sound disk. The cone has a conical peripheral wall with a flat base. The flat base has a diameter smaller than the sound disk. The sound disk is adhered to the conical peripheral wall of the cone, defining with the flat base a sound chamber. When used in a speaker, the invention eliminates the installation of an end block in the casing, and therefore the size and weight of the speaker are greatly reduced. The sounder can be used with a cover, a vibration diaphragm, an inner body, a cushion, and cap to form a compact sound head.